"This Is Us" spoilers and theories have been slowing circulating online, and some fans believe that the stray dog that Jack and Rebecca found in the final moments of last week's episode could have something to do with Jack's shocking and tragic death. Recently, actor Milo Ventimiglia, who plays Jack Pearson on the hit NBC family drama, seemed to hint that the dog could play an important part on the show, and some fans believe it could be the key to understanding the show's big mystery.

Milo Ventimiglia wants you to pay attention to the dog

According to reports, Milo Ventimiglia opened up about the dog that Jack and Rebecca found in last week's episode, saying that the dog can be seen in a scene of the big three after Jack's death.

"Whose dog is it? You never heard about a dog," the actor teased, seemingly dropping a hint that fans should pay attention to the dog. Now, "This Is Us" fans are speculating that the dog could actually be the reason why Jack died.

Is the dog the key to Jack's death?

According to the latest "This Is Us" fan theory, Jack may have died in the fire that destroyed the Pearson family home when he went back inside the burning house to try to save the family dog. As many viewers know, Kate has expressed guilt over her father's death in the past, and even claimed that it was her fault that her father died. Could it be that Kate begged Jack to go back into the house to save the dog from the fire, and lost his own life instead?

Why does Kate feel responsible?

Of course, there are other options as well. Perhaps the dog somehow started the fire by knocking over a burning candle or chewing a cord. Maybe Kate feels bad because she wanted to keep the stray dog in the first place, or it could be possible that something Kate did lead to the fire, like using a hot hair styling tool.

There are so many unanswered questions when it comes to "This Is Us" and Jack's death. Viewers are chomping at the bit to find out what happened to the Pearson family patriarch, but since the show likes to take their time telling the family's story through bits and pieces and flashbacks, it looks like it will be awhile before fans find out what really happened to Jack.

Meanwhile, "This Is Us" fans are continuing to tune in week after week, which is making the show one of the most popular on television. The stellar cast and interesting storytelling don't hurt either. To find out how it all plays out, tune in on Tuesday nights at 9 p.m. on NBC.